Among 11 patients who presented as blind in early infancy, with Leber's congenital amaurosis (5 patients), optic nerve hypoplasia (4 patients), or macular colobomata (2 patients), 8 developed visually guided behavior and measurable grating acuity by age 5 to 46 months. All children with measurable grating acuity demonstrated visually guided mobility. Grating acuity was predictive of later visual performance in 10 of 11 patients by age 12 to 16 months. The best grating acuity attained by 7 months was 1.3 to 3.0 cycles/degrees (20/460 to 20/200) and 0.13 cycles/degrees (20/4700) by month 8. Two patients with Leber's congenital amaurosis and one with optic nerve hypoplasia remained blind. No clinical features existed to differentiate these three patients from the eight whose visual status improved. Posterior visual pathway maturation may underlie the improvement.